Apparatus, including those commonly referred to as “3D printers”, have been proposed as a potentially convenient way to produce three-dimensional objects. These apparatus typically receive a definition of the three-dimensional object in the form of an object model, or data derived from an object model. This object model (or data derived therefrom) is processed to form instructions, which control the apparatus to produce the object using at least one production material. Depending on the type of 3D printer, these production materials may comprise a combination of agents and powdered build materials, heated polymers and/or liquid solutions of production material. The processing of an object model (or data derived therefrom) may be performed on a layer-by-layer basis. It may be desired to produce a three-dimensional object with at least one property, such as color, mechanical and/or structural properties. The processing of the object model (or data derived therefrom) may vary based on the type of apparatus and/or the production technology being implemented. Generating objects in three-dimensions presents many challenges that are not present with two-dimensional print apparatus.